1. Field of the Invention
This invention relates in general to lighting devices and in particular to lighting devices used to illuminate a surface.
2. Description of the Prior Art
There are virtually hundreds of different types of lighting devices which are known to the art. Although these may range from the simplicity of a miniature light bulb to the sophistication of a motion picture lighting set, the function of each device is the same--to produce light for illumination of a surface. Associated with certain lighting devices is a reflector which collects a majority of the light rays coming from the source of light and guides this collected light in a particular direction. Systems typical of this type of operation are automobile headlamps, flashlights, and lighthouse beacons. Such systems may also incorporate lenses to further concentrate or focus the guided light.
Other lighting devices may employ the use of a pulsing or intermittent light source to repeatedly switch from an illuminating mode to an off mode. A stroboscope operates on this principal as do flashing neon signs and fluorescent lamps. Still other lighting devices used in the scientific or testing field employ the use of a stationary light source which is repeatedly reflected either by a rotating mirror arrangement or by a rotating mirror in combination with a static optical system. An example of such a system is disclosed in the U.S. Pat. No. 3,972,583, to Lobb.
One disadvantage with lighting devices whose only purpose is to illuminate an area is that if a reflector and/or lens is not used, a large portion of the light output may be lost by illuminating surfaces for which illumination is not desired. When a reflector is used, normally the lumens per square inch of light intensity are decreased in proportion to the increase in area which is being illuminated. Similarly, with a diverging stationary light source the distance of a surface from the source governs the intensity of the illumination of that surface. Lighting devices such as that of Lobb which incorporate sophisticated optics and a moving light beam are typically not used for conventional illumination but rather are used in association with scientific experimentation and scientific equipment.